Thread cutting and retaining device for circular knitting machines

ABSTRACT

A thread cutting and retaining device for circular knitting machines for the manufacture of stockings and the like, suitable for employing stretch, elastic and normal type yarns, comprising at least one thread suction nozzle on a fixed structure above the dial of the circular knitting machine, at least one cutting element near said nozzle and at least one feed. The device further comprises a mechanical thread retaining unit on the periphery of said fixed structure formed from a clamp-like element with fluid control means for said clamp-like element in the open position and clamp-like element return means in the closed position.

United States Patent 1 [111 3,760,608 Lonati Sept. 25, 1973 THREADCUTTING AND RETAINING 3,097,512 7/1963 Moyer 66/140 5 DEVICE FORCIRCULAR KNITTING 3,367,146 2/1968 A1lred..... 66/140 S UX MACHINES3,379,036 4/1968 Farmer 66/145 R [75] Inventor: Francesco Lonati,Brescia, Italy FOREGN PATENTS OR APPLICATIONS 7 2 7 B [73] Assignee:Construzioni Meccaniche Lonati di Loy/'22 H96 Great mam S Lona"Francesco Brecla Italy Primary ExaminerRobert R. Mackey [22] Filed: May28, 1971 Attorney-Guido Modiano and Albert Josif 21 Appl. No.: 147,981

, [57] ABSTRACT [30] Foreign li i p i Data A thread cutting andretaining device for circular knit- June 16 1970 Ital 26041 N tingmachines for the manufacture of stockings and the y like, suitable foremploying stretch, elastic and normal 52 U.S. Cl 66 s 66 5 type YamsmPr1smg at least thread Int Cl D04b/15/61 zle on a fixed structure abovethe dial of the circular [58] Fieid S 145 s knitting machine, at leastone cutting element near said 6/l45 nozzle and at least one feed. Thedevice further com- I prises a mechanical thread retaining unit on theperiph- References Cited ery of said fixed structure formed from aclamp-like e1- ement with fluid control means for said clamp-like ele-UNITED STATES PATENTS ment in the open position and clamp-like elementre- R25,584 5/1964 Stack et a1 66/140 S tum means i h l d position2,908,154 10/1959 Butler 66/145 S UX 3,077,097 2/1963 Butler 66/140 8 3Claims, 5 Drawing Figures PATENIEUSEPZSISH 3.760.608

sum 1 or 2 I NVE NTOR FRANCESCO LONATI M NH PATENTED8EP25I973 V a 760608 sumaorz l THREAD CUTTING AND RETAINING DEVICE FOR CIRCULAR KNITTINGMACHINES BACKGROUND OF THE INVENTION This invention relates to a threadcutting and retaining device for circular knitting machines with severalfeeds for the manufacture of stockings and the like.

At the present state of the art, in circular knitting machines for themanufacture of stockings and the like, pneumatic suction nozzles areprovided to retain the thread after it has been cut, or when it is notsubjected to processing in such a way so as to then allow an easyrecovery of the thread when it must again be used for the knitting .ofthe tubular manufactured article.

In these machines, to the above mentioned suction nozzles, cuttingdevices are associated, arranged in a position close to the trajectoryof the needles, in a way that the cutting occurs near the last stitchcarried out by the needles on the thread to be cut. The cutting meansare arranged downstream from the nozzles, considering the rotationaldirection of the needle cylinder, and somewhat close to the nozzles.

Said thread cutting and retaining means have however variousdisadvantages, when the machine has four or more feeds. In particular,such disadvantages are made more evident as the number of feedsincreases, a higher number of feeds being increasingly in request in thepresent art for a more rapid manufacture of the stockings or socks.

In fact, in a machine with many feeds, these feeds must be arranged veryclose along the periphery of the needle cylinder, so that some of themare necessarily very near to the cutting devices. In this way thefeeding thread, or yarn cut by the cutting elements, has very short freeend, so that it becomes very difficult, if not impossible, to make itsretention secure by the suction of the relative nozzle. This factinvolves still more serious problems in that the thread is'tensionedduring the cutting operation and once the cutting has been carried out,it is abruptly released. This releasing can result in unthreading of theyarn off the thread guide, such an effect being increased by the brakingaction which is exercised on the thread upstream of the thread guide.

In other words, with the multifeed machines, it is difficult to possiblyguarantee, for all the feeds, a secure retaining of the thread by meansof the suction-nozzles and, thus a secure manufacturing, without spoiledwork and machine stops.

The non-retained thread cannot then be hooked by the needles forsubsequent processing thereof.

The problem mentioned above is then still more serious when theso-called stretch thread is used for the manufacture of stockings,having a particular elasticity. With the machines having more than fourfeeds at present in use, manufacturing with such a type of thread ispractically impossible.

SUMMARY OF THE INVENTION One object of the present invention is that ofeliminating the above mentioned disadvantages by providing a threadcutting and retaining device to be applied to circular knitting machineswith several feeds for the manufacture of stockings and the like, whichallows in every case the retaining of each thread, from any feed, andwhich also allows in a satisfying way the processing of the so-calledstretch yarns.

Another object of the present invention is that of conceiving a deviceof the above mentioned type which may be easily installed, even onmultifeed circular machines already in use.

A further object of the invention is that of providing a thread cuttingand retaining device of secure operation and economic production.

According to the invention, there is provided a thread cutting andretaining device for circular multifeed knitting machines for themanufacture of stockings and the like, particularly those having fourand more feeds, comprising at least one thread suction nozzle arrangedon a fixed structure mounted above the hook carrying dial of thecircular knitting machine, at least one cutting element arranged nearsaid at least one nozzle donwstream thereof relative to the rotationaldirection of the needle cylinder, as well as at least one feedcorresponding to said at least one suction nozzle, the device having amechanical thread retaining unit cooperating with said at least onesuction nozzle arranged on the periphery of said fixed structure at afeed upstream from said cutting element, and formed from a substantiallyclamp-like element for the reception of the thread not in use.Preferably fluid operated control means of said clamp-like element inthe open position is provided as well as return means for saidclamp-like elements to the closed position.

BRIEF DESCRIPTION OF THE DRAWING The invention will better appear fromthe description of a preferred but not exclusive embodiment of theinvention, illustrated by way of an indicative and not limitativeexample in the accompanying drawings in which:

FIG. 1 is a side view of the unit carrying the cutting and retainingdevice according to the invention, arranged above the dial,

FIG. 2 is a view from below the device, according to the invention, thedial being removed,

FIG. 3 is aplan view of the device showing the relationship between theelements of the device and the feeds of the thread, and

FIGS. 4 and 5 show at a larger scale and in a perspective view a detailof the retaining means in closed and in open positions, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENT With reference to the abovementioned figures, the present device comprises a thread retaining unitincluding a multiarm lever or clamp element la rotatable about a pin 2and having one end 3 loaded by a spring 4. This spring is fixed to aplate element 4a, in turn mounted on a fixed structure 7 at 4b, at whichpoint a resilient tang 40 also terminates, which acts on the leverelement or plate-like element 1a. The other two ends of said plate-likeelement are shown at 5 and 6, respectively. On the structure 7, thereare two plate-like elements of the above mentioned type, symmetricallyarranged with respect to the axis of the structure 7 carrying the unit.On the base 7a, there are'further provided two inclined notches 7b, oneat each of the plate-like elements la, in such a way so as to be freelyaccessible to the thread when these plate-like elements are in the openposition, corresponding to that shown by broken lines in FIG. 1. On thebase 7a there are also provided holes 8 from which two suction nozzles 9and 10 lead,

within which end spouts 9a and 10a of two canals 9b and 10b open.

For the operation of the retaining devices 1, pneumatic devices 11 areprovided (in FIG. 1 only one has been shown), one for each retainingunit 1, terminating with a projecting end 12 in contact with the end 5of the plate-like element la.

The device according to the invention further comprises a cuttingelement visible in FIG. 1 and generally indicated at 13, arranged alittle after the retaining device l, in the rotational direction of theneedle cylinder. Said cutting element is formed from a cutting blade 14,rigid with a rod 15, movable in a vertical direction and guided in ahole provided in a structural frame a. A spring 150 wound around the rod15 at the upper part thereof, pushes a cutting blade 14 towards thebottom having locations from one part on the structure 15a and from theother on a block element 15b, rigid to the rod 15.

On the dial there is fixed a so-called milling cutter 22, cooperatingwith the cutting element 13, in the direction in which the blade 14slides'on the flat upper surface of the milling cutter and cuts off thethread which is hooked and dragged into the teeth of the milling cutterwhen it is withdrawn from active feeding position.

Rigid to the base 7a is also a retaining unit of the socalled elastictype shown at 16 and comprises a rod 17 ending with a square end 18housed in nonoperative condition, in a suitable slot or seat 19 providedin the base 70. The rod 17 is vertically guided in the structure 7. Aspring 21 winds around a portion of said rod 17, tending to maintain itin a raised position shown in FIG. 1, that is with the end 18 housed inthe seat 19.

The operation of the thread retaining and cutting device according tothe invention is illustrated in the following, by making referencefirstly to the case of knit ting thread of normal and of so-called.stretch" type, and then to the case of knitting thread of the so-calledelastic type, this latter being used for the manufacture, for instance,of the elastic upper zone of the stockings.

The sequence of the cutting and retaining operations in the caseconcerning normal yarn and in the case concerning stretch yarn, ifwithdrawal of the yarn from active feeding position is desired is thefollowing: first of all the thread guide is raised and a simultaneousaction of the element 11 on the plate-like element 1a takes place in thedirection to bring it into the open or first position shown by brokenlines in FIG. 1, in which the notch 7b remains freely accessible to thethread. Following the rotation of the needle cylinder and the raising ofthe thread guide, the thread is drawn by the teeth of the milling cutter22 and contacts the blade 14 which cuts it off. At this point the freeend of the thread begins to feel the effects of the suction nozzle,which tends to bring it towards the center of the device, making it beintroduced into the notch 7b, as shown in FIG. 5. A command from unit 11frees the plate-like element 1a which, under the action of the spring 4,is carried into a second position shown by the continuous line in FIG.1, clamping the thread in the notch 7b, as shown in FIG. 4. In this waythe thread is securely held and is impeded from any possible detachingfrom said notch by the thread guide. In particular, this advantageouslyoccurs when the thread from the feed which is the nearest to theretaining device 1, is cut. In fact, the cut thread, whose end is veryshort (it should be remembered that on the periphery of the structure 7there are arranged, for example, eight feeds as shown in FIG. 3), mightnot sufiiciently feel the effects of the return action of the nozzle andcould, both for its elasticity and for the restraining exercised on itupstream from the thread guide, escape from the thread guide whichsupports it.

When the thread must be changed, for example, from one type of thread toanother type, or in general, always when a thread must be introducedinto the process, there is lowered first the relative thread guide, in away to knit the thread, and then the retaining device 1 with a commandfrom the pneumatic device 11 is opened so that the end of the thread inquestion is freed.

It is understood, that in the same notch 7b, several threads may be heldsimultaneously from the same feeding unit.

The resilient tang 40 serves to press the plate-like element 1a againstthe structure 7, in such a way to assure the secure retaining of thethreads.

During the sucking phase of the thread supported by the thread guidenearest to the retaining device 1, for a thread which has already beencut, the sucking action is increased by blowing air through the spouts9a or 10a, in a way to improve the sucking effect on the thread. Thesucking in the canals 9 and 10 is continuous.

If it is desired now to carry out the same operation for the elasticthread, which is introduced into the manufacturing for certainparticular parts of the socks or stockings, the procedure is partly asfor the normal thread or the stretch-thread, only that the retainingdevice 1 is no longer made use of, but the device 17 is used instead. Infact, for the insertion of the elastic thread, the relative thread guideis lowered and, when the thread has been knitted, the rod 17 is loweredwhich frees the thread held in it.

For the exclusion of the elastic thread, first of all the thread guideis lifted and the lowering of the rod 17 is operated, while the threadis hooked in it. At this point, the return of the hook, in the positionin which the appendix 18 is placed in its seat 19, is operated, withwhich the retaining of the elastic thread is obtained, and the cuttingof the thread in the way already said for the normal thread is provided.

As can be seen, the device according to the invention allows secureretaining for each type of thread and for all the threads of all thefeeds. In particular, the threads of the feeds farthest from the cuttingdevice can be held by the single sucking effect of one of the twonozzles, as occurs in conventional machines having a small number offeeds, because the free end of the cut thread is sufficiently long to beable to be held without difficulty.

The cutting and retaining device thus described is susceptible tonumerous modifications and changes, all falling within the scope of theinvention. Thus the number of retaining and cutting units may bedifferent from two, as has been assumed in the example described.

The materials used, as well as the dimensions and the shapes of thevarious elements forming the invention, may be any according to therequirements.

I claim:

I. In a circular knitting machine for the manufacture of stockings andthe like, including a needle cylinder, at least one feed for a thread tobe knitted, a hook carrying dial and support structure arranged abovesaid dial, a thread cutting and retaining device including meansarranged to cut said thread and to retain the cut end portion of saidthread, respectively, said cutting means comprising a circular toothedblade coaxial to said dial and a cutting blade arranged on said supportstructure for cooperation with said circular toothed blade for cuttingthe thread, and said retaining means comprising at least a suctionnozzle for holding the end portion of said thread cut by said cuttingmeans, a clamp element pivoted on said support structure and asubstantially inclined notch provided on said support structure adjacentsaid clamp element for receiving said end portion cut by said cuttingmeans and sucked by said suction nozzle, said clamp element having anoperative portion movable from a first position in which said portionleaves said notch accessible to said end portion of the thread to asecond position in which said portion closes said notch clamping saidend portion of the thread arranged therein, means being provided foractuating said clamp element to move from said first position to saidsecond position and from said second position to said first position.

2. A device as claimed in claim 1, wherein said clamp element comprisesa plate-like element having three arm portions extending in threedifferent directions, said plate-like element being povoted on saidsupport structure substantially tangentially to said dial, the first ofsaid arms being provided with said operative portion laterally coveringsaid notch in said second thread retaining position, and wherein saidmeans for actuating said clamp element comprise resilient means actingon a second of said arms and fluid operated means acting on a third ofsaid arms against the action of said resilient means.

3. A device as claimed in claim 1, wherein said retaining means furthercomprise a resilient tang anchored to said support structure and havinga free end in contact with said operative portion of said clamp element,said tang urging said element towards said support structure forincreasing the clamping action on said thread.

1. In a circular knitting machine for the manufacture of stockings andthe like, including a needle cylinder, at least one feed for a thread tobe knitted, a hook carrying dial and support structure arranged abovesaid dial, a thread cutting and retaining device including meansarranged to cut said thread and to retain the cut end portion of saidthread, respectively, said cutting means comprising a circular toothedblade coaxial to said dial and a cutting blade arranged on said supportstructure for cooperation with said circular toothed blade for cuttingthe thread, and said retaining means comprising at least a suctionnozzle for holding the end portion of said thread cut by said cuttingmeans, a clamp element pivoted on said support structure and asubstantially inclined notch provided on said support structure adjacentsaid clamp element for receiving said end portion cut by said cuttingmeans and sucked by said suction nozzle, said clamp element having anoperative portion movable from a first position in which said portionleaves said notch accessible to said end portion of the thread to asecond position in which said portion closes said notch clamping saidend portion of the thread arranged therein, means being provided foractuating said Clamp element to move from said first position to saidsecond position and from said second position to said first position. 2.A device as claimed in claim 1, wherein said clamp element comprises aplate-like element having three arm portions extending in threedifferent directions, said plate-like element being povoted on saidsupport structure substantially tangentially to said dial, the first ofsaid arms being provided with said operative portion laterally coveringsaid notch in said second thread retaining position, and wherein saidmeans for actuating said clamp element comprise resilient means actingon a second of said arms and fluid operated means acting on a third ofsaid arms against the action of said resilient means.
 3. A device asclaimed in claim 1, wherein said retaining means further comprise aresilient tang anchored to said support structure and having a free endin contact with said operative portion of said clamp element, said tangurging said element towards said support structure for increasing theclamping action on said thread.